Image forming device having a mechanism for driving a fixing roller

Abstract

An image forming device, configured to form an image on a sheet in an electrophotographic method, includes a fixing roller thermally fixing a developer image on the sheet, a driving unit generating a driving force, a first rotating body configured to be driven by the driving force and rotate the fixing roller, a clutch mechanism provided on a power transmission route to transmit the driving force from the driving unit to the first rotating body, the clutch mechanism switching between a state to transmit the driving force to the first rotating body and a state to block transmission of the driving force to the first rotating body, a second rotating body provided at a downstream side relative to the clutch mechanism on the power transmission route so as to rotate in conjunction with the first rotating body, a detecting unit detecting whether the second rotating body is rotating.

1. An image forming device configured to electrophotographically form an image on a sheet, the image forming device comprising:
 a fixing roller configured to rotate in contact with the sheet and thermally fix a developer image transferred onto the sheet while feeding the sheet; 
 a driving unit configured to generate a driving force; 
 a first rotating body configured to be driven by the driving force generated by the driving unit and rotate the fixing roller; 
 a clutch mechanism provided on a power transmission route on which the driving force is transmitted from the driving unit to the first rotating body, the clutch mechanism being disposed downstream of the driving unit and upstream of the first rotating body on the power transmitting route, the clutch mechanism being configured to switch between a state for transmitting the driving force to the first rotating body and a state for blocking transmission of the driving force to the first rotating body; 
 a second rotating body provided on a downstream side route, wherein the downstream side route corresponds to a route at a downstream side of the clutch mechanism on the power transmission route, the second rotating body being configured to rotate in conjunction with the first rotating body; and 
 a detecting unit disposed to face the second rotating body at the downstream side of the clutch mechanism on the power transmitting route, the detecting unit being configured to detect whether the second rotating body is rotating to indirectly detect whether the fixing roller is rotating. 
 
     
     
       2. The image forming device according to  claim 1 , further comprising a third rotating body provided on the downstream side route, the third rotating body being configured to transmit the driving force while in contact with the first rotating body,
 wherein the second rotating body is different from the third rotating body. 
 
     
     
       3. The image forming device according to  claim 2 ,
 wherein the first to third rotating bodies are gears. 
 
     
     
       4. The image forming device according to  claim 2 ,
 wherein the downstream side route includes a first route and a second route, wherein the power transmission route diverges at the third rotating body into the first and second routes, 
 wherein the first rotating body is provided on the first route, and 
 wherein the second rotating body is provided on the second route. 
 
     
     
       5. The image forming device according to  claim 4 ,
 wherein the second rotating body is provided farther from the third rotating body than any other rotating body on the second route. 
 
     
     
       6. The image forming device according to  claim 1 ,
 wherein the detecting unit includes an optical sensor, and 
 wherein the optical sensor includes a light emitting element and a light receiving element. 
 
     
     
       7. The image forming device according to  claim 6 ,
 wherein the detecting unit is provided on a side of a side face of the second rotating body to detect a rotational state of the second rotating body. 
 
     
     
       8. The image forming device according to  claim 7 ,
 wherein the second rotating body includes a projection provided on the side face of the second rotating body, the projection being configured to protrude in a direction parallel to an rotational axis of the second rotating body, the projection being configured to revolve around the rotational axis of the second rotating body in an integral manner with the second rotating body, and 
 wherein the detecting unit is configured such that the light emitting element faces the light receiving element face via the projection in a radial direction of the second rotational direction. 
 
     
     
       9. The image forming device according to  claim 8 ,
 wherein the projection is provided at an outermost circumferential side on the side face of the second rotating body. 
 
     
     
       10. The image forming device according to  claim 9 ,
 wherein the light emitting element of the detecting unit is disposed outside the projection in the radial direction of the second rotating body, and 
 wherein the light receiving element of the detecting unit is disposed inside the projection in the radial direction of the second rotating body. 
 
     
     
       11. The image forming device according to  claim 8 ,
 wherein the second rotating body has a diameter larger than a diameter of any other rotating body on the downstream side route. 
 
     
     
       12. The image forming device according to  claim 1 , further comprising a fixing unit that includes the fixing roller and a heater configured to generate heat for thermally fixing the developer image on the sheet. 
     
     
       13. The image forming device according to  claim 12 ,
 wherein the fixing roller is integrated with the heater.